Bromination is the process where an alkene is halogenated with bromine. The purpose of this experiment was bromination of stilbene to stilbene dibromide. The element bromine is toxic and requires maximum care when used. Bromine was generated in the reaction mixture by using a green method. Less hazardous reagents were used to do so. This can be seen by the chemical reaction 2HBr+H_2 O_2→〖Br〗_2+2H_2 O. Hydrogen peroxide is used to oxidize HBr to 〖Br〗_2. By adding hydrogen peroxide this can make working with bromine less dangerous. This experiment is a greener approach to the bromination process because ethanol was used as a solvent. Ethanol is nontoxic making the experiment less harmful.
The identity of the product and unknown were 4-tert-butylbenzyl phenol ether and tert-butyl phenol respectively. The key to making this discovery was the melting point and TLC results! The substitution reaction was successful but not fully effective.
The goal of the experiment is to synthesize a bromohexane compound from 1-hexene and HBr(aq) under reflux conditions and use the silver nitrate and sodium iodide tests to determine if the product is a primary or secondary hydrocarbon. The heterogeneous reaction mixture contains 1-hexene, 48% HBr(aq), and tetrabutylammonium bromide and was heated to under reflux conditions. Heating under reflux means that the reaction mixture is heated at its boiling point so that the reaction can proceed at a faster rate. The attached reflux condenser allows volatile substances to return to the reaction flask so that no material is lost. Since alkenes are immiscible with concentrated HBr, tetrabutylammonium bromide is used as a phase-transfer catalyst. It forms a complex with HBr and extracts it from the aqueous phase into the organic phase where the alkene is. This dehydrates the acid, making it more reactive so that the addition reaction is possible. Rapid stirring is required in order to maximize the surface area
The literature melting point range of methyl trans-cinnamate is ~34-38oC (Aldrich).4 The obtained melting point of the crude was 34.5-35.5oC, which is a highly narrow range of less than 1oC difference and it also falls within the expected melting point range. Hence, the crystal lattice structure of the product is largely intact, requiring an even amount of thermal energy to melt the sample. The experimental melting point range indicates the crude product is relatively pure with minimal impurities. The percent yield was satisfactory, having a 68% yield. To optimize this yield, consider the steps in how the reagents are introduced to the reaction mixture in terms. It is understood the mechanism is acid-catalyzed where protons coordinate with the carbonyl oxygen to make the carbonyl carbon more electropositive for nucleophilic attack (Scheme 1). In the experimental procedure all reactants were added together, this is inefficient as the protons can coordinate with either trans-cinnamic acid or methanol. Coordination with methanol is unnecessary as it reduces its nucleophilicity and makes less protons available to coordinate with the carboxylic acid. To improve
In this experiment, it was possible to produce the major products from bromination of acetanilide and aniline. 0.075g of 4-bromoacetanilide and 0.156g of 2,4,6-tribromoanilne were collected from bromination of 0.07g acetanilide and 0.05g aniline with the percent yield of 67.57% and 88.1% respectively. At the end of the experiment, to prove the formation of the major products, melting point of the products were measured. The melting point of the product from the bromination of acetanilide was 164.8-168.50c, which is in the range of the melting point of 4-bromoacetanilide, 165-1690c, as reported on the Chemical Book, CAS Database List (chemicalbook.com). The melting point of the product from the bromination of aniline was 119.8-121.90c, which is in the range of the melting point of 2,4,6-tribromoaniline, 120-1220c, as indicated on PubChem, Open Chemistry Database (pubchem.ncbi.nlm.nih.gov). This verified the formation of the major products. Overall, one can say that the experiment was
Wilfrid Laurier University Chemistry Department. Fall 2014. Acetylsalicylic Acid (Aspirin) Synthesis. Pages 96-98 in Chemistry 110 Lab Manual. Wilfrid Laurier University, ON, Canada.
The following formulas in Figure 5 were used to determine the depression in the freezing point was used to determine the molality of the solution, the moles of the solute present, the molar mass of the solute, and finally the unknown, in respective order.
If impure, preform recrystallization procedure to remove the impurities. Then calculate Percent Recovered on crystals formed, and preform melting point procedure.
The purpose of this lab was to properly prepare a Grignard reagent from an unknown aryl halide and then to use the prepared Grignard reagent with solid carbon dioxide and an acid quench to form a carboxylic acid.
The purpose of this experiment was identifying two compounds in an unknown mixture via liquid-liquid extraction and acid-base reactions. The compounds in the unknown mixture isolated by using recrystallization, and then their identity was determined by comparing the experimental melting point values with actual melting points. Unknown mixture 5 contained a carboxylic acid, 4-methylbanzoic acid, and a non-ionizable organic compound, 1,2-diphenylethane-1,2-dione.
Tetraphenylcyclopentadienone (0.100 g, 0.260 mmol), dimethyl acetylenedicarboxylate (0.1 mL), and nitrobenzene (1 mL) were placed in a small reaction tube along with a boiling stick. The reaction tube was heated to a reflux using a sand bath until the purple soln. turned a tan color. When the soln. was warm to touch, ethanol (3 mL) was stirred in. Next the reaction tube was placed in ice. The material was collected using vacuum filtration. The resulting solid was washed with ethanol and the color was white. Once the product was dried completely, the weight was taken (0.078 g, 0.235 mmol,
The purpose of this experiment was to identify the two components of an unknown mixture through diverse experimental techniques such as recrystallization, extraction, melting point, and acid-base reactions. From this, the group to which these two compounds belong to had to be determined. These groups are: Carboxylic Acids, phenols, and neutrals. By determining the melting points of the two unknown compounds, these values were compared to the values of melting points in the chart and the proper compound was selected. For the case of this experiment, the unknown mixture contained, 4-methylbenzoic acid. The neutral was not determined due to inaccuracies during the experiment.
Which is the same as potassium chloride as potassium chlorides melting point is 770 degrees Celsius. “Part B” experiment was to figure out the water percentage of the unknown salt “579” and the results of this test after some calculations was that there was 0.024% of H2O inside of salt “579”. This percentage is very low and out of the 8 salts its closes to zero percent water. Potassium chlorides water percentage is zero which only helps prove the point that the salt “579” is potassium chloride. In “Part C” the density of the salt was calculated, and it turned out to be 1.73 g/mL and compared to the 8 known salts it could be potassium chloride which is 1.98 g/mL or calcium chloride dehydrate 1.85 g/mL. Considering the other 6 characteristics of calcium chloride dehydrate there is no way this is possible because its water percentage is 24.5% and salt “579” water percentage is 0.024%. The least reliable test result was “Part D” the heat of solution of salt “579” which was significantly different from potassium chlorides heat of solution. The heat solution of salt “579” was -2.44 kcal/mol and the heat solution of potassium chloride is 4.404
Determination of melting point is important as it is an indication of the limit of safe storage. Take both ends open glass capillary tubes. Introduce sufficient amount of lipstick into each of 5 capillary tubes, about 10mm high and allow the tubes to stand for the appropriate time and at the prescribed temperature in capillary tube apparatus. The temperature at which the lipstick begin to melt in the capillary tube is taken as the melting point. Repeat the operation 5 times using other 5 capillary tubes and record the result.
Blends were prepared by mixing all the excipients. The blends were evaluated for different parameters and it was observed that moisture content was NMT 3% for each blend, Carr's Index (%) was in the range of 13.44±0.02 to 16.20±0.03, Hausner's